NAME

SYNOPSIS

DESCRIPTION

[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the
requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to
the ISO C standard.

The function call nan("n-char-sequence") shall be equivalent to:

strtod("NAN(n-char-sequence)", (char **) NULL);

The function call nan("") shall be equivalent to:

strtod("NAN()", (char **) NULL)

If tagp does not point to an n- char sequence or an empty string, the function call shall be equivalent
to:

strtod("NAN", (char **) NULL)

Function calls to nanf() and nanl() are equivalent to the corresponding function calls to strtof() and strtold().

RETURN VALUE

These functions shall return a quiet NaN, if available, with content indicated through tagp.

If the implementation does not support quiet NaNs, these functions shall return zero.